Biomedical coatings

The use of surface covering layers (i.e. coatings) provides methods to control the biological response to materials and material devices including implants and prostheses (Figure 1). Depending on implant location and function, implants require specific biological responses. For instance, bone implants require fast integration with native bone tissue. On the other hand, soft tissue implant functionality is improved by the absence of a contractile fibrous tissue capsule. The aim of our research on biomaterial coatings is to optimize the biological response for specific applications of biomedical implants.

Organic coatings

Several types of organic materials can be used to generate a coating with specific modulatory effects on the biological response. Examples include proteins, DNA, sugars, etc. Specific biological responses that can be controlled are cell attachement and behavior. Organic coatings consisting of proteins are generally based on the presence of these proteins at the implant location. Members of the extracellular matrix (ECM) are the most commonly used proteins. DNA is interesting as a structural molecule, as it is homogeous within all vertebrate species. Consequently, as an implant coating, it masks the implant from being recognized as a foreign body.

Morphology of DNA-based coatings, generated using Layer-by-Layer deposition.

Inorganic coatings

Interesting inorganic materials for coating generation include bioactive ceramics such as calcium phosphates and silica-based bioglasses. Bioactive materials allow direct apposition of bone tissue without an intervening soft tissue layer. Consequently, these materials are frequently used to coat bone implants. At the Department of Biomaterials, several deposition techniques are being investigated for this purpose, including radiofrequent magnetron sputtering and Electrostatic Spray Deposition (ESD).

Further improvement of the clinical efficacy of biomedical coatings is sought in functionalization of biomedical coatings with appropriate biological compounds (growth factors/antibiotics/etc.) using synthesis low-temperature strategies that preserve the functional properties of co-deposited biological agents.

Key references

1. de Jonge LT, Leeuwenburgh SCG, van den Beucken JJJP, Wolke JGC, Jansen JA. Electrosprayed enzyme coatings as bioinspired alternatives to bioceramic coatings for orthopedic and dental implants. Adv Func Mater 2009;19:1-8.
2. van den Beucken JJ, Walboomers XF, Boerman OC, Vos MR, Sommerdijk NA, Hayakawa T, Fukushima T, Okahata Y, Nolte RJ, Jansen JA. Functionalization of multilayered DNA-coatings with bone morphogenetic protein 2. J Control Release. 2006;113(1):63-72.
3. Leeuwenburgh SCG, Wolke JGC, Siebers MC, Schoonman J, Jansen JA. In vitro and in vivo reactivity of porous, electrosprayed calcium phosphate coatings. Biomaterials 2006;27(18):3368-78.